Mechanisms for transforming a continuous rotary movement into an intermittent rotarymovement



June 9. 1964 a. o. J. s. MORNER 3,136,167 MECHANISMS NSFORMING A CONTINUOUS ROTARY VEMENT I INTERMITTENT ROTARY M MENT Filed Feb. 20, 2 Sheets-Sheet 1 INVENTOR BENGT OLOF JOHAN STELLA" M O RNER ATTORNEY 5 June 9. 1964 B. o. J. s. MORNER 3,136,167

MECHANISMS FOR TRANSFORMING A CONTINUOUS ROTARY MOVEMENT INTO AN INTERMITTENT ROTARY MOVEMENT Filed Feb. 20, 1962 2 Sheets-Sheet 2 Fig. 3

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ATTORNEY 6' United States Patent MECHANISMS FOR TRANSFORMING A CONTINU- OUS ROTARY MOVEMENT INTO AN INTERMIT- TENT ROTARY MOVEMENT Bengt Olof Johan Stellan Miirner, Gotenborg, Goteborg and Bohus, Sweden, assignor to Aktiebolaget Partner, Gunnebogatan, Molndal, Sweden Filed Feb. 20, 1962, Ser. No. 174,521 Claims priority, application Sweden Apr. 18, 1961 2 Claims. (Cl. 74-125) The present invention relates to a mechanism for transforming a continuous rotary movement into an intermit tent, or stepwise, rotary movement. More specifically the present invention relates to mechanisms of this kind wherein a continuously driven eccentric reciprocates a push rod which in turn actuates stepping means for the stepwise rotation of a shaft.

According to the present invention, said stepping means comprises a ratchet Wheel secured to the shaft which is to be rotated intermittently and a leaf spring having one end in one-way driving engagement with said ratchet wheel, said push rod imparting to said spring a movement which causes the ratchet wheel to be intermittently rotated. Also the opposite end of the spring may according to the invention be arranged to lie against the periphery of the ratchet wheel.

In one embodiment of the present invention the spring has mainly the shape of a U embracing the ratchet wheel with both ends in engagement therewith and having its middle portion connected to the push rod.

According to a second embodiment of the present invention, the spring is made in the form of a yoke with legs of different length having its middle portion immovably mounted and having its longer leg adapted to transfer the push rod movement to the ratchet wheel and resiliently pressing against the end of the push rod.

In the last-mentioned embodiment there may be pro vided a second leaf spring placed within said first-mew tioned spring and having its legs terminating a distance from the free ends of the legs of said first-mentioned spring.

The invention is illustrated in the accompanying drawings wherein:

FIG. 1 shows a mechanism according to one embodiment of the present invention,

FIG. 2 illustrates a second embodiment,

FIG. 3 is a view mainly corresponding to FIG. 2 and to a larger scale illustrating a further embodiment of the present invention,

FIG. 4 illustrates a manner to interconnect the two leaf springs used in the embodiment according to FIG. 3, and

FIG. 5 is a cross section to a larger scale taken along the line VV in FIG. 4.

It is to be understood that there are numerous applications for the mechanism according to the present invention, but for purposes of explanation and illustration only it is assumed here that the mechanism according to the present invention will be used for driving an oil pump for a portable motor-driven chain saw. The type of oil pump considered comprises a piston member which is at the same time reciprocable and rotatable in a cylinder and which is provided with a shaft portion projecting out of the cylinder and intended to be rotated intermittently. Since the oil pump and other parts of the chain saw do not form any part of the present invention, only certain details of the pump and of the chain saw are shown in the drawings.

In FIGS. 2 and 3 the housing of an oil pump of the type outlined above is indicated by reference numeral 1. The pump piston which is not shown in the drawing is provided with a shaft portion 2 projecting out of the housing and adapted to be rotated intermittently in order 3,136,167 Patented June 9, 1964 to cause stepwise longitudinal displacement of the piston. There is further provided a push rod 3 which has its lower end lying against an eccentric 4 which is mounted on the motor shaft or other shaft driven by the motor and which causes the push rod 3 to be moved longitudinally forward and backward once for each full turn of the motor shaft. By means of the stepping device to be described herebelow the movement of the push rod will be transmitted to the shaft 2 in the form of a stepwise rotating movement in such a manner, that the piston will move only a small portion of its stroke for each revolution of the motor.

Common to all of the embodiments illustrated in the drawings is a ratchet wheel 5 secured to the shaft 2. In FIG. 1 numeral 6 designates a portion of the motorsaw casing which is provided with a through-bore for the push rod 3. In a recessed portion 7 of this through-bore there is provided, around the push rod 3, a compression spring 8 which has its lower end lying against an abutment 9 on the push rod and the upper end of which abuts against the under side of a bushing 10 of plastic or the like which is inserted in a still wider portion of the through-bore at the upper end thereof. The spring 8 keeps the lower end of the push rod 3 in engagement with the eccentric 4, so that the push rod 3 will be raised by the eccentric against the action of the spring 8 under the action of which the push rod will thereafter be moved back downwardly. At its upper end the push rod 3 carries a U-shaped leaf spring 13 which is attached to. the push rod end by means of a screw 12 inserted in a threaded bore 11 in the push rod. The spring 13 has its middle portion connected to the push rod and the legs 14, 15 of the spring embrace the ratchet Wheel 5. One leg 14 of the spring 13 is adapted to engage the teeth of the ratchet wheel at one side thereof while the other leg 15 has an end portion 15a which is bent and positioned for engaging the ratchet wheel at a point substantially diametrically opposite the point of engagement of the leg 14. When the push rod 3 is moved upwardly under the action of the eccentric 4 from the position shown in FIG. 1, the leg 14 of the spring 13 will rotate the ratchet wheel and thereby the shaft 2 and the pump piston connected thereto in counterclockwise direction according to the drawing, and when the push rod is moving downwardly the bent portion 15a of the second leg of the sp'rm-g will engage one tooth of the ratchet wheel when moving downwardly and thereby cause a further rotation in counter-clockwise direction of the ratchet wheel. For each reciprocatory movement of the push rod 3, that is for each revolution of the motor shaft, the ratchet wheel 5 will thus be rotated a small angle which causes a small axial displacement of the reciprocating pump piston.

In the embodiment according to FIG. 2 the spring 13 of FIG. 1 is replaced by a yoke-shaped leaf spring 16 with legs of different length and having its middle portion immovably mounted in a recess 17 in the pump housing 1 in such a way, that its longer leg 18 which has a bentaround end portion 18a lying against the periphery of the ratchet wheel 5 and against the under side of which the upper end of the push rod 3 abuts will urge the push rod towards the eccentric 4. Thus, besides transferring the movement from the push rod 3 to the ratchet wheel 5 the spring leg 18 in this embodiment also serves as a return spring for the push rod 3. The other, shorter leg 19 of the spring 16 is lying against the periphery of the ratchet wheel 5 and serves as a pawl for preventing the ratchet wheel being rotated in the wrong direction. In this embodiment the ratchet wheel 5 and thereby the pump piston is rotated one step for each upward movement of the push rod 3 and will be retained during the downward movement of the push rod by the spring leg 19.

In certain cases it may be'desirable to reduce wear on the ratchet wheel 5 by reducing the pressure of the spring legs 18 and 19 against the periphery of the ratchet wheel. At the same time, however, a comparatively large force is required in the spring leg 18 to keep the push rod 3 against the eccentric 4.

v In such a case the device illustrated in FIG. 3 may be used. In the embodiment of FIG. 3 the thickness of the spring 16 has been reduced, whereby. the pressure against the ratchet wheel has been reduced, and within the spring 16 there is provided a second spring 20 of thicker material and of substantially the same shape as the spring 16 and which is enveloped by spring 16. The legs 21 and 22 of spring 20 terminate a distance from the ends of the corresponding legs 18 and 19, respectively, of the spring 16. Hereby a sufficient spring pressure on the upper end of the push rod 3 is obtained, while at the same time the spring pressure on the ratchet wheel has been reduced. To fix the two springs 16 and 20 relative to each other one may use a clamp 23 bent around the springs as shown in FIGS. 4 and 5 and secured by means of punching with a center punch as at 24 (see FIG. 5).'

The present invention is not limited to the embodiments hereinbefore described and as shown in the accompanying drawings, said embodiments being susceptible of various modifications with respect to its details without departing from the spirit of the invention. For example, the ratchet wheelprovided on the shaft 2 of the pump piston may be replaced by serrations formed directly on the shaft 2.

What I claim is: v 1. A mechanism for transforming a continuous rotary movement into an intermittent rotary movement, comprising a rotatably mounted ratchet Wheel, a substantially C-shaped leaf spring having its middle portion immovably mounted and having a long leg and a shorter leg, a push rod, a rotatably driven cam having an end of said push rod slideably positioned thereon whereby said push rod is moved upon the rotation of said cam, said longer spring leg resiliently pressing against the other end of said push rod retaining said push rod first end on said cam and having its free end in one-Way driving engagement with said ratchet wheeLsaid shorter spring leg having its free end positioned against said ratchet wheel forming a pawl co-operating with said ratchet wheel.

2. In a mechanism, as claimed in claim 1, a second leaf spring of a similar configuration to said first-mentioned leaf spring superimposed thereon, the legs of said second spring being shorter than the legs of said first-mentioned leaf spring, and terminating a distance from the free ends of said legs of said first-mentioned spring and means retaim'ng said springs together.

References Cited in the file of this patent UNITED STATES PATENTS 1,080,637 Kenworthy Dec. 9, 1913 1,738,909 Kurz Dec. 10, 1929 1,750,456 Borm Mar. 11, 1930 2,272,929 Barth Feb. 10, 1942 2,324,844 Hutt July 20, 1943 2,595,967 McCloy May 6, 1952 2,667,079 Muller Jan. 26, 1954 2,942,486 Beguin June 28, 1960 3,034,363 Vogel May 15, 1962 FOREIGN PATENTS 580,046 Great Britain Aug. 26, 1946 

1. A MECHANISM FOR TRANSFORMING A CONTINUOUS ROTARY MOVEMENT INTO AN INTERMITTENT ROTARY MOVEMENT, COMPRISING A ROTATABLY MOUNTED RATCHET WHEEL, A SUBSTANTIALLY C-SHAPED LEAF SPRING HAVING ITS MIDDLE PORTION IMMOVABLY MOUNTED AND HAVING A LONG LEG AND A SHORTER LEG, A PUSH ROD, A ROTATABLY DRIVEN CAM HAVING AN END OF SAID PUSH ROD SLIDEABLY POSITIONED THEREON WHEREBY SAID PUSH ROD IS MOVED UPON THE ROTATION OF SAID CAM, SAID LONGER SPRING LEG RESILIENTLY PRESSING AGAINST THE OTHER END OF SAID PUSH ROD RETAINING SAID PUSH ROD FIRST END ON SAID CAM AND HAVING ITS FREE END IN ONE-WAY DRIVING ENGAGEMENT WITH SAID RATCHET WHEEL, SAID SHORTER SPRING LEG HAVING 